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(without typos) from the publisher. Not indexed. Not
illustrated.1898 Excerpt: ... CHAPTER IV. THE ECOLOGICAL AND
BIOLOGICAL RELATIONS OF THE NATURAL GROUPS. Habitat groups.--When
species are looked at from the point of view of phylogeny and
taxonomy, they are classified in the several groups of the natural
system; when looked at from the point of view of the effect of
habitat and of environment upon the plant-body, they are divided
into vegetation forms; when considered with reference to the
habitats in which they occur, they are arranged in habitat groups.
All of these are groups of species. When we look at the floral
covering and attempt to distinguish its constituent parts, we find
them set off in formations. A formation is a piece of the floral
covering, not a group of species. A habitat group is a group of
species, which are subject to similar physical conditions, and
frequent like habitats. While the term habitat group has been
restricted to a group of species put together by reason of
occurrence in like habitats, it might be applied to a different
conception, namely, to the aggregate of individuals found within a
certain habitat. The latter application of the term would be more
natural, but in such case the conception of a habitat group would
correspond closely to that of a formation, and the two terms would
be synonyms. In dealing with a flora phytogeographically, it is
desirable to regard it from several standpoints. Since the
conception of the habitat group here adopted permits us to consider
the flora from an additional point of view, and to express the part
played by the various species to better advantage, it has been
preferred. Habitat groups, whether looked at from the one
standpoint or the other, are determined primarily with reference to
certain physical factors. By far the most important of these is the
water content of...